The present disclosure relates to a wireless feeding system of a noncontact feeding system in which power is supplied and received on a noncontact (wireless) basis.
An electromagnetic induction system is known as a system for supplying power on a wireless (radio) basis.
In addition, a wireless feeding and charging system using a system referred to as a magnetic field resonance system utilizing an electromagnetic resonance phenomenon has recently been drawing attention.
In the case of the noncontact feeding system of the electromagnetic induction system already used widely now, a magnetic flux needs to be shared between a feeding source and a feeding destination (power receiving side), the feeding source and the feeding destination need to be disposed in very close proximity to each other to transmit power efficiently, and a coupling axial alignment is also important.
On the other hand, the noncontact feeding system using the electromagnetic resonance phenomenon has advantages of enabling power transmission at a longer distance than the electromagnetic induction system and not decreasing transmission efficiency very much even when axial alignment is somewhat poor, due to the principles of the electromagnetic resonance phenomenon.
Incidentally, in addition to the magnetic field resonance system, there is an electric field resonance system utilizing the electromagnetic resonance phenomenon.
Japanese Patent Laid-Open No. 2001-185939 (hereinafter referred to as Patent Document 1), for example, discloses a wireless feeding system employing the magnetic field resonance system.
According to the technique disclosed in Patent Document 1, power is transmitted from a feeding coil connected to a feeding circuit to a resonant coil by electromagnetic induction, and frequency adjustment is made by a capacitor and a resistance connected to the resonant coil.
There has recently been a report on a radio power transmission technique that has achieved transmission of a power of 60 W at a distance of 2 m using the magnetic field resonance system utilizing the resonance phenomenon of a magnetic field.
In addition, there has been a report on the development of a highly efficient “wireless feeding system” that transmits a power of 60 W using the magnetic field resonance system and which drives an electronic device at a distance of 50 cm.
This radio power transmission technology enables radio power transmission of a few 10 W at a distance of a few m, and is thus expected to be applied to new concept products for use in offices and households.